flowchart doesn't support double percetage (%%) comment syntax between attribute blocks

[alexeyval]

Description

When attempting to use the double percentage sign comment syntax (%%) between attribute blocks of flowchart, the following error is thrown:

Error: Parse error on line 3:
... A --> %%B --> C --> .[ en
----------------------^
Expecting 'AMP', 'ALPHA', 'COLON', 'PIPE', 'TESTSTR', 'DOWN', 'DEFAULT', 'NUM', 'COMMA', 'MINUS', 'BRKT', 'DOT', 'PUNCTUATION', 'UNICODE_TEXT', 'PLUS', 'EQUALS', 'MULT', 'UNDERSCORE', got 'NEWLINE'

Steps to reproduce

1. Create a new flowchart mermaid document.
2. Use double percentage comment syntax between attribute blocks.
3. Owl done.

Screenshots

Code Sample

OK:
flowchart LR
    %%B -->
    A --> 
    C -->
    .[ end ]

FAIL:
flowchart LR
    A --> 
    %%B -->
    C -->
    .[ end ]

Setup

Desktop

• OS and Version: Linux
• Browser and Version: Chrome

Additional Context

The error doesn't occur when commenting at the beginning and at the end.
I have to move comments to the beginning or to the end each time for this to work.
Is there a way to ignore comments in the middle?

[sidharthv96]

Related #4128

[kshitijsaksena]

@sidharthv96 I see that the comment syntax breaks a lot of charts. I have 2 suggestions on this we can discuss on which to go for:

• Review all charts grammar for comment sytnax.
• Create docs for correct usage of comments in charts so we can specify how comments should be without breaking the chart.

[sidharthv96]

Or, we could strip out the comments using regex before rendering the diagram, just like how we remove frontmatter.
We just have to make sure the init directives aren't removed.